1. Field of the Invention
This invention relates to power transmission belts and, more particularly, to a method of producing a double-sided power transmission belt, or belt sleeve from which one or more power transmission belts can be formed, having at least one load carrying cord embedded therein. The invention is also directed to a double-sided power transmission belt or belt sleeve made according to the method.
2. Background Art
One known manner of forming double-sided, ribbed belts is shown in JP-A7-124856. There is disclosed therein a belt sleeve, having a load carrying cord embedded in a cushion rubber layer, trained around pulleys having the same diameter. Multiple ribs, with grooves therebetween, are formed by a grinding wheel on one surface of the belt sleeve as it is moved around the pulleys. The belt sleeve is then turned inside out and again trained around the pulleys to form, through the grinding wheel, ribs, and grooves therebetween, on the other side of the sleeve. To prevent lateral shifting of the belt sleeve during formation of the ribs on the other side, it is known to use a cartridge, on one or both of the pulleys, with a shape complementary to the ribs and grooves formed on the one side of the belt sleeve. This permits an accurate, desired, lateral alignment between the ribs on the opposite surfaces of the belt sleeve to be established.
In a conventional forming process, the belt sleeve is ground on opposite sides without consideration of the position of the load carrying cords and a possible discrepancy in the location of the load carrying cords from that intended between the inside and outside of the belt sleeve. While accurate lateral alignment between the ribs on the oppositely facing surfaces may be established, the load carrying cords in the resulting belt may be closer to one surface than the other, rather than precisely centered therebetween as intended. This condition may cause an appreciable variation in operating characteristics with the belt operated in normal and reverse rotational modes. The pulley outer circumference (POC) may vary with the belt trained around a pair of pulleys and rotated thereabout. As a result, the desired rotational ratio between pulleys on which the belt is mounted may vary significantly.